This invention relates to flatbed scanners in general and more specifically to a system for securing the moveable carriage of a flatbed scanner.
Scanner devices, such as flatbed scanners, are well-known in the art and produce machine-readable image data signals that are representative of a scanned object, such as a photograph or a page of printed text. In a typical scanner application, the image data signals produced by a scanner are used by a personal computer to reproduce an image of the scanned object on a suitable display device, such as a CRT or a printer.
A typical flatbed scanner may include illumination and optical systems to accomplish scanning of the object. The illumination system illuminates a portion of the object (commonly referred to as a xe2x80x9cscan regionxe2x80x9d), whereas the optical system collects light reflected by the illuminated scan region and focuses a small area of the illuminated scan region (commonly referred to as a xe2x80x9cscan linexe2x80x9d) onto the surface of a photosensitive detector positioned within the scanner. Image data representative of the entire object is obtained by sweeping the scan line across the entire object, usually by moving the illumination and optical systems with respect to the object, although other arrangements are possible.
By way of example, the illumination system may include a light source (e.g., a fluorescent or incandescent lamp or an array of light emitting diodes (LEDs)). The optical system may include a lens and/or mirror assembly to focus the image of the illuminated scan line onto the surface of the detector. Alternatively, a xe2x80x9ccontact image sensorxe2x80x9d (CIS) may be used to collect and focus light from the illuminated scan region onto the detector.
The photosensitive detector used to detect the image light focused thereon by the optical system may be a charge-coupled device (CCD), although other devices may be used. A typical CCD may comprise an array of individual cells or xe2x80x9cpixels,xe2x80x9d each of which collects or builds-up an electrical charge in response to exposure to light. Since the quantity of the accumulated electrical charge in any given cell or pixel is related to the intensity and duration of the light exposure, a CCD may be used to detect light and dark spots on an image focused thereon.
Regardless of the particular types and configurations of the illumination and optical systems, a typical flatbed scanner mounts the illumination system and at least a portion optical system to a moveable carriage assembly that is mounted within the housing of the flatbed scanner so that the carriage assembly can be moved back and forth underneath the transparent platen of the scanner. A drive system operatively associated with the carriage assembly moves the carriage assembly back and forth underneath the scanner platen to accomplish scanning of the object.
One problem associated with flatbed scanners of the type just described relates to the unwanted movement of the carriage assembly during transport or shipping of the flatbed scanner. Excessive movement of the carriage assembly during shipping or transport can upset the alignment or calibration of the system, possibly requiring that the system be re-aligned or re-calibrated before the scanner can be placed in service. In extreme cases, excessive movement of the carriage assembly can physically damage the carriage assembly and/or drive system, requiring repair or replacement of the damaged components before the scanner can be placed in service.
In an effort to ameliorate the foregoing problems, various types of restraining devices or shipping locks have been developed to prevent the unwanted movement of the carriage assembly during shipping or transport of the scanner. Chief among such restraining devices are screw and/or clamp assemblies, although other types of devices may be used. Typically, such devices secure the carriage assembly to the frame or chassis of the scanner, thereby substantially reducing the likelihood that the carriage assembly will be damaged during subsequent shipping or transport of the flatbed scanner. While such restraining devices or shipping locks are generally effective from a functional standpoint, they must be removed before the scanner may be used. Besides being time-consuming to accomplish (and usually requiring the use of separate tools), some users may damage the carriage and/or drive system in the process of removing the shipping locks if they are careless or if they do not have the required skills. Still other users may fail to remove the shipping restraints altogether, often leading them to erroneously conclude that the scanner device is defective.
Consequently, a need remains for a system for securing the moveable carriage of a flatbed scanner that does not suffer from the disadvantages associated with conventional shipping lock or restraining devices. Ideally, such a system for securing the carriage assembly should be inexpensive to implement, yet be easily disengaged by the user, preferably without requiring the use of separate tools. Still other advantages could be realized if such a system could be easily re-engaged to allow a user to later move the scanner to another location without fear of damaging the carriage assembly and/or drive system.
A scanning system according to one embodiment of the present invention may comprise a housing having a transparent platen provided thereon. A scanner device operatively associated with the housing is moveable along a displacement path. A drive system comprising a drive belt connected to the scanner device and a tensioning system operatively associated with the drive belt moves the scanner device along the displacement path. A control system operatively associated with the drive system actuates the drive system to move the scanner device to a stowed position along the displacement path. The location of the stowed position is such that a force exerted on the scanner device and directed along the displacement path is not transmitted to the drive belt tensioning system.
Also disclosed is a method for securing a carriage within a scanner that comprises: Providing a scanner device having a carriage assembly therein that is operatively associated with a drive system so that the carriage assembly is moveable along a displacement path, the drive system including a drive belt and a drive belt tensioning system operatively associated with the drive belt; and moving the carriage to a stowed position along the displacement path, the location of the stowed position being such that a force exerted on the carriage and directed along the displacement path is not transmitted to the drive belt tensioning system.